The present invention generally relates to electrically conductive springs useful in devices and assemblies requiring an electric pathway between spaced components. The invention more particularly relates to embodiments of such springs having at least two electrically conductive coils which establish an electric circuit between components such as a power source and a load which may move relative to the power source.
Many devices and assemblies are known which require wired electrical pathways between components. In some of these devices and assemblies, one or more of the components may move relative to the other in which case the electrical pathway must accommodate for the movement without breaking. While a simple insulated wire or wire bundle may be sufficiently flexible to accommodate for the movement, for components that move frequently or constantly, and particularly those which move at a high frequency, the wires may quickly fatigue and break thereby causing an open circuit condition.
Although the present invention may be useful in any number of devices, one type of device requiring an electrically wired connection between movable components is a closed cycle cryogenic cooler which is commonly used to cool devices such as infrared detectors. There is seen in FIG. 1 a prior art linear compressor 100 having first and second pistons 112 and 114 which reciprocate toward and away from each other to compress a working gas within the space 116 between the piston heads. Movement of the pistons toward each other compresses the gas which is directed out of the compressor through gas line 118 to a working device such as an expander (not shown). The reciprocating movement of the pistons 112 and 114 is controlled through a motor coil 120 and 122, respectively, which, when energized, move relative to stationary magnets 124, 126, respectively. Pistons 112, 114 connect to coils 120, 122 via connecting elements 128, 130, respectively. Springs 132, 134 are provided between connecting elements 128, 130 and housing end walls 136, 138 to support and provide linear stability along the reciprocating paths of the pistons 112, 114, respectively. In order to provide electricity to motor coils 120, 122, respective electrical leads 140, 142 are provided which, although shown in fragmented view, must be connected to wiring which leads to an external power source (not shown). Since the motor coils are moving with their respective pistons, wire leads 140, 142 (and their associated wiring leading to the power source) undergo repetitive flexing eventually causing fatigue and possible breakage.
There therefore remains a need for an improved apparatus and method for establishing a durable flexible electric circuit between two or more components where one or more of the components is moving relative to the other, for example in a reciprocating motion along a linear path.